In general, a magnetic recording/reproducing apparatus having a rotary type head drum such as a digital video camcorder is provided with a motor assembly. The head drum is supported by a shaft. The motor assembly is disposed at the upper part or the lower part of the shaft and is used to rotate the head drum. Recently, a print motor assembly is used as the motor assembly with a view to reduce the overall size and weight of the apparatus.
One of head drum assemblies employing the prior art print motor assembly is shown in FIG. 1. As shown, the head drum assembly 10 includes a fixed shaft 12, a head drum 14 rotatably supported by the fixed shaft 12 through a bearing 16 and, a print motor assembly 20.
The print motor assembly 20 includes a lower rotor yoke 22, a permanent magnet 24, a printed circuit board stator winding 26 (hereinafter, PCB stator winding 26), and an upper rotor yoke 28. The PCB stator winding 26 as used herein refers to a circuit board including a dielectric board with lead wires disposed on one or more sides of the dielectric board.
The lower rotor yoke 22 is seated on an inside of the head drum 14 and the permanent magnet 24 is mounted on the lower rotor yoke 22.
The permanent magnet 24 has a plurality of magnetic pole pairs arranged at equal angular spacings, wherein each pair of the magnetic pole pairs is equally magnetized so that the north and the south poles thereof are of equal strength.
The PCB stator winding 26 is secured to the fixed shaft 12 using a flange 30. To be more specific, after the PCB stator winding 26 is mounted on a stepped portion 32 of the flange 30, the flange 30 is tightly fitted around the fixed shaft 12. Thereafter, the flange 30 and the PCB stator winding 26 are joined with each other by soldering. Further, the PCB stator winding 26 is electrically connected with a flexible connector 34 for transmitting a motor driving signal through a soldered portion 36.
The upper rotor yoke 28 is seated on a shoulder 18 of the head drum 14 using an adhesive bonding or the like.
When the motor driving signal is transmitted onto the PCB stator winding 26 through the flexible connector 34, the PCB stator winding 26 rotates the head drum 14 in conjunction with the permanent magnet 24.
However, there are a number of problems associated with the above described print motor assembly. First all, the above mentioned arrangement of the print motor assembly is not adapted to a rotary shaft. Further, it is easy for the connector for transmission of the motor driving signal to come into a contact with the upper rotor yoke.